40 results on '"Shi-Xian Qu"'
Search Results
2. Impact of time delays and environmental noise on the extinction of a population dynamics model
- Author
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Shi-Xian Qu, Tao Yang, and Chun Zhang
- Subjects
Physics ,education.field_of_study ,Extinction ,Stochastic resonance ,Population ,Condensed Matter Physics ,Regular Article - Statistical and Nonlinear Physics ,Shift time ,Electronic, Optical and Magnetic Materials ,Noise ,Population model ,Quantitative Biology::Populations and Evolution ,Carrying capacity ,Statistical physics ,education ,Environmental noise - Abstract
In this paper, we examine a population model with carrying capacity, time delay, and sources of additive and multiplicative environmental noise. We find that time delay, noise sources and their correlation induce regime shifts and transitions between the population survival state and the extinction state. To explore the transition mechanism between these two states, we analyzed the shift time to extinction, or the delayed extinction time, of populations. The main finding is that the extinction transition time as a function of the noise intensity shows a maximum, indicating the existence of an appropriate noise intensity leading to a maximal delayed extinction. This nonmonotonic behavior, with a maximum, is a signature of the noise-enhanced stability phenomenon, observed in many physical and complex metastable systems. In particular, this maximum increases (or decreases) as the cross-correlation intensity or the delay time in the death process increases. Furthermore, the signal-to-noise ratio as a function of noise intensity shows a maximum, which is a signature of the stochastic resonance phenomenon in the population dynamics model investigated in the presence of time delay and environmental noise. Graphic abstract
- Published
- 2021
3. Transition of phase order in coupled map systems
- Author
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Shi-Xian Qu, Bin Zhang, and Jun Liu
- Subjects
Physics ,Coupling constant ,010308 nuclear & particles physics ,Stochastic process ,Phase (waves) ,Chaotic ,General Physics and Astronomy ,01 natural sciences ,Instability ,Chaos theory ,010305 fluids & plasmas ,0103 physical sciences ,Statistical physics ,Bifurcation ,Coupled map lattice - Abstract
By studying the time series of logistic maps, dark lines in bifurcation diagrams and cobweb diagrams, characteristics of sequential iterations of the map are found. Before the merging together two chaotic bands, sequential iterations of the map present an ordered state. After that, with the instability of the hyperstable periodic orbit, sequential iterations of the map appear disordered. Therefore, the statistical results of time correlation of direction phase are introduced to describe the transition of the collective behaviour. Based on the two-dimensional coupled map lattice, the relationship between bifurcation parameters and order parameters with the change of coupling strength is studied. We show that when the coupling strength is weak, the critical bifurcation parameters are positively correlated with the coupling strength. When the coupling strength is large, the phase order of the system is not affected by the coupling strength. The transition of collective behaviour in a modular network is also studied. By fixing modularity and bifurcation parameters, with the change of coupling strength, the collective behaviour presents a transition process from spatiotemporal chaos to phase-ordered state. There are periodic orbits in the spatiotemporal chaotic region. A phase synchronisation region can be present in the antiphase synchronisation region. Furthermore, there exist multistable solutions in the region.
- Published
- 2021
4. Publisher's Note: 'Predicting phase and sensing phase coherence in chaotic systems with machine learning' [Chaos 30, 083114 (2020)]
- Author
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Junjie Jiang, Shi Xian Qu, Chun Zhang, and Ying-Cheng Lai
- Subjects
CHAOS (operating system) ,Phase coherence ,Computer science ,Chaotic systems ,Applied Mathematics ,Phase (waves) ,General Physics and Astronomy ,Statistical and Nonlinear Physics ,Statistical physics ,Mathematical Physics - Published
- 2020
5. Predicting phase and sensing phase coherence in chaotic systems with machine learning
- Author
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Chun Zhang, Shi Xian Qu, Junjie Jiang, and Ying-Cheng Lai
- Subjects
Lyapunov function ,Computer science ,Phase (waves) ,Chaotic ,General Physics and Astronomy ,Lyapunov exponent ,Machine learning ,computer.software_genre ,01 natural sciences ,010305 fluids & plasmas ,Machine Learning ,symbols.namesake ,0103 physical sciences ,010306 general physics ,Mathematical Physics ,Oscillation ,business.industry ,Applied Mathematics ,Reservoir computing ,Statistical and Nonlinear Physics ,Phase synchronization ,Orders of magnitude (time) ,Nonlinear Dynamics ,symbols ,Artificial intelligence ,Electronics ,business ,computer - Abstract
Recent interest in exploiting machine learning for model-free prediction of chaotic systems focused on the time evolution of the dynamical variables of the system as a whole, which include both amplitude and phase. In particular, in the framework based on reservoir computing, the prediction horizon as determined by the largest Lyapunov exponent is often short, typically about five or six Lyapunov times that contain approximately equal number of oscillation cycles of the system. There are situations in the real world where the phase information is important, such as the ups and downs of species populations in ecology, the polarity of a voltage variable in an electronic circuit, and the concentration of certain chemical above or below the average. Using classic chaotic oscillators and a chaotic food-web system from ecology as examples, we demonstrate that reservoir computing can be exploited for long-term prediction of the phase of chaotic oscillators. The typical prediction horizon can be orders of magnitude longer than that with predicting the entire variable, for which we provide a physical understanding. We also demonstrate that a properly designed reservoir computing machine can reliably sense phase synchronization between a pair of coupled chaotic oscillators with implications to the design of the parallel reservoir scheme for predicting large chaotic systems.
- Published
- 2020
6. Effect of network structural perturbations on spiral wave patterns
- Author
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Xingang Wang, Shi Xian Qu, Ying-Cheng Lai, Xiang Gao, Yafeng Wang, and Dongmei Song
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Physics ,Applied Mathematics ,Mechanical Engineering ,Open problem ,Aerospace Engineering ,Ocean Engineering ,Link (geometry) ,Complex network ,Network dynamics ,01 natural sciences ,Stability (probability) ,Synchronization ,010305 fluids & plasmas ,Control and Systems Engineering ,0103 physical sciences ,Statistical physics ,Electrical and Electronic Engineering ,Spiral (railway) ,010306 general physics ,Topology (chemistry) - Abstract
Dynamical patterns in complex networks of coupled oscillators are of both theoretical and practical interest, yet to fully reveal and understand the interplay between pattern emergence and network structure remains to be an open problem. Among the many outstanding issues, a fundamental one is how the network structure affects the stability of dynamical patterns. To address this issue, we focus on the spiral wave patterns and investigate the effects of systematically added random links on their stability and dynamical evolutions. We find that, as the network structure deviates more from the regular topology and thus becomes increasingly more complex, an originally stable spiral wave pattern can disappear but different types of patterns can emerge. In addition, short-distance links added to a small region containing the spiral tip can have a more significant effect on the wave pattern than long-distance connections. As more random links are introduced into the network, distinct pattern transitions can occur, such as the transition of the spiral wave pattern to a global synchronization state, to a chimera-like state, or to a pinned spiral wave. About the transition points, the network dynamics are highly sensitive to small structural perturbations in that the addition of even a single link can change the pattern from one type to another. These findings provide additional insights into the pattern dynamics in complex networks, a problem that is relevant to many physical, chemical, and biological systems.
- Published
- 2018
7. Disappearance and reappearance of chaos
- Author
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Bin Zhang, Sheng-Jun Wang, and Shi-Xian Qu
- Subjects
Physics ,Chaos (genus) ,biology ,General Physics and Astronomy ,Statistical and Nonlinear Physics ,Lorenz system ,biology.organism_classification ,Computer Science Applications ,Nonlinear Sciences::Chaotic Dynamics ,symbols.namesake ,Computational Theory and Mathematics ,symbols ,Statistical physics ,Rayleigh scattering ,Mathematical Physics - Abstract
The disappearance and reappearance of chaos by adjusting the internal parameters of dynamics in Lorenz system are studied. We observe monotonous and periodic time-dependent changes of Rayleigh number. There exists relaxation time for the disappearance of chaos, when we use the snapshot attractors to observe the change of the system attractors. We show that the rate of disappearance and reappearance of chaos is positively correlated with the control parameters. To reflect the relaxation phenomenon of chaotic disappearance and the sensitivity of trajectory, the concept of finite-time Lyapunov exponent is used. Then the statistical characteristics of the system can be presented by standard deviation. The chaotic disappearance and reappearance are manifested in the decrease and increase of the standard deviation. The standard deviation decreases continuously during chaotic disappearance, but increases discontinuously during chaotic reappearance. A distinctive scenario is that no matter which parameter changes, when we use the same rate of change in the process of chaotic disappearance and reappearance, their paths are different.
- Published
- 2021
8. Optically- and thermally-induced electronic transitions in a three-level system
- Author
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Wei Jin, Chun Li, Georgios Lefkidis, Ming-Yang Qiu, Wolfgang Hübner, and Shi-Xian Qu
- Subjects
Materials science ,Atomic electron transition ,Atomic physics ,Condensed Matter Physics ,Mathematical Physics ,Atomic and Molecular Physics, and Optics ,Three level ,Molecular electronic transition - Published
- 2020
9. Transition of synchronization of coupled maps in modular networks
- Author
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Bin Zhang, Sheng-Jun Wang, Shi-Xian Qu, and Ru-Hai Du
- Subjects
Modularity (networks) ,business.industry ,Computer science ,Transition (fiction) ,General Physics and Astronomy ,Statistical and Nonlinear Physics ,Modular design ,Topology ,Phase synchronization ,01 natural sciences ,010305 fluids & plasmas ,Computer Science Applications ,Computational Theory and Mathematics ,0103 physical sciences ,Synchronization (computer science) ,010306 general physics ,business ,Mathematical Physics ,Phase diagram - Abstract
Spatiotemporal patterns in the transition of phase synchronization in modular networks of coupled logistic maps are studied. The phase diagram of spatiotemporal patterns is presented by analyzing both the collective behavior of direction-phase and the changes of links connecting clusters of different phases. The spatiotemporal chaos is obtained when the coupling strength is weak. We show that the spatiotemporal chaos can be composed by clusters in periodic states. The region of periodic behaviors is independent of modularity. Then with decreasing coupling or increasing modularity, the system presents the same transition path from complete synchronization to cluster synchronization, except the network is close to fully connected networks. There are two distinctive scenarios from disordered behavior to an ordered state when the modularity ratio varies from one to zero. First, for networks with small modularity, the number of phase synchronized clusters decreases with the increasing of the coupling strength. Second, for networks with large modularity, the number of phase-synchronized clusters nonmonotonically changes with the coupling strength.
- Published
- 2019
10. Transition to high-dimensional chaos in nonsmooth dynamical systems
- Author
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Ying-Cheng Lai, Ru Hai Du, and Shi Xian Qu
- Subjects
Physics ,Dynamical systems theory ,Transition (fiction) ,Periodic attractor ,FOS: Physical sciences ,Interval (mathematics) ,High dimensional ,Parameter space ,Nonlinear Sciences - Chaotic Dynamics ,01 natural sciences ,010305 fluids & plasmas ,CHAOS (operating system) ,Nonlinear Sciences::Chaotic Dynamics ,0103 physical sciences ,Statistical physics ,Chaotic Dynamics (nlin.CD) ,010306 general physics ,Bifurcation - Abstract
We uncover a route from low-dimensional to high-dimensional chaos in nonsmooth dynamical systems as a bifurcation parameter is continuously varied. The striking feature is the existence of a finite parameter interval of periodic attractors in between the regimes of low- and high-dimensional chaos. That is, the emergence of high-dimensional chaos is preceded by the system's settling into a totally nonchaotic regime. This is characteristically distinct from the situation in smooth dynamical systems where high-dimensional chaos emerges directly and smoothly from low-dimensional chaos. We carry out an analysis to elucidate the underlying mechanism for the abrupt emergence and disappearance of the periodic attractors and provide strong numerical support for the typicality of the transition route in the pertinent two-dimensional parameter space. The finding has implications to applications where high-dimensional and robust chaos is desired., 9 pages, 8 figures
- Published
- 2018
11. Microwave dielectric properties of Mg 2 TiO 4 ceramics synthesized via high energy ball milling method
- Author
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Lin Cheng, Peng Liu, Shi-Xian Qu, Lei Cheng, and HuaiWu Zhang
- Subjects
Materials science ,Microwave dielectric properties ,Mechanical Engineering ,Metallurgy ,Metals and Alloys ,Evaporation ,law.invention ,Chemical engineering ,Mechanics of Materials ,law ,visual_art ,Phase (matter) ,X-ray crystallography ,Materials Chemistry ,visual_art.visual_art_medium ,Calcination ,Particle size ,Ceramic ,Ball mill - Abstract
Li2MgTiO4 ceramics were prepared with Li2CO3, TiO2 and MgO by high energy ball mill method. After mixtures ball-milling 30 h and calcining at 700°C, the homogenate Li2MgTiO4 powders with average particle size of 160 nm were obtained. The pure phase obtained temperature was about 300°C lower than that by a conventional solid-state reaction process. Due to Li+ evaporation, the Li2MgTiO4 ceramics sintered at high temperature existed with some Mg2TiO4. The Li2MgTiO4 ceramics at 1250°C had an excellent microwave dielectric properties ϵr = 12.17, Q × f = 42000 GHz and an τf = −23 ppm/°C
- Published
- 2015
12. Dynamics of spiral waves rotating around an obstacle and the existence of a minimal obstacle
- Author
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Xia Feng, Shi-Xian Qu, Xingang Wang, Xiang Gao, Hong Zhang, and Teng-Chao Li
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Computer science ,Quantitative Biology::Tissues and Organs ,Dynamics (mechanics) ,01 natural sciences ,Instability ,010305 fluids & plasmas ,Vortex ,Classical mechanics ,General theory ,Obstacle ,Spiral wave ,0103 physical sciences ,Spiral (railway) ,010306 general physics - Abstract
Pinning of vortices by obstacles plays an important role in various systems. In the heart, anatomical reentry is created when a vortex, also known as the spiral wave, is pinned to an anatomical obstacle, leading to a class of physiologically very important arrhythmias. Previous analyses of its dynamics and instability provide fine estimates in some special circumstances, such as large obstacles or weak excitabilities. Here, to expand theoretical analyses to all circumstances, we propose a general theory whose results quantitatively agree with direct numerical simulations. In particular, when obstacles are small and pinned spiral waves are destabilized, an accurate explanation of the instability in two-dimensional media is provided by the usage of a mapping rule and dimension reduction. The implications of our results are to better understand the mechanism of arrhythmia and thus improve its early prevention.
- Published
- 2017
13. Microwave dielectric properties of AWO4 (A=Ca, Ba, Sr) ceramics synthesized via high energy ball milling method
- Author
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Huaiwu Zhang, Peng Liu, Shi-Xian Qu, and Lin Cheng
- Subjects
High energy ,Materials science ,Microwave dielectric properties ,Mechanical Engineering ,Metallurgy ,Metals and Alloys ,Solid-state ,Microstructure ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Scheelite ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Ceramic ,Particle size ,Composite material ,Ball mill - Abstract
The AWO4 (A = Ca, Sr, Ba) compounds with scheelite structure were synthesized by high energy ball milling for 30 min and the average particle size was reduced to about 120 nm after milling 30 h. AWO4 ceramics were well sintered at relatively low temperatures of 900–1000 °C, 200–400 °C lower than those required by a conventional solid state reaction technique. The samples of CaWO4, SrWO4, and BaWO4 ceramics have dense microstructures and excellent microwave dielectric properties, ɛr = 10.7, 8.6, 8.4; Q × f = 62,100 GHz, 57,500 GHz, 58,800 GHz; and τf = −48 ppm/°C, −52 ppm/°C, −64 ppm/°C, respectively.
- Published
- 2013
14. Phase order in one-dimensional piecewise linear discontinuous map
- Author
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Tao Jin, Ru-Hai Du, Shi-Xian Qu, and Sheng-Jun Wang
- Subjects
Mathematical analysis ,Phase (waves) ,General Physics and Astronomy ,Order (ring theory) ,Space (mathematics) ,01 natural sciences ,010305 fluids & plasmas ,Piecewise linear function ,Distribution (mathematics) ,Phase space ,0103 physical sciences ,010306 general physics ,Scaling ,Mathematics - Published
- 2018
15. Hot Electrons and Electron-Phonon Coupling in a Cylindrical Nanoshell
- Author
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Shi-Xian Qu, Ya-Ni Zhao, Michael R. Geller, and Lin Zhang
- Subjects
Materials science ,Condensed matter physics ,business.industry ,Phonon ,Biomedical Engineering ,Shell (structure) ,Bioengineering ,General Chemistry ,Electron ,Radius ,Condensed Matter Physics ,Nanoshell ,Molecular vibration ,Free surface ,General Materials Science ,business ,Thermal energy - Abstract
We use a standard model for the low-temperature electron-phonon interaction in metals to calculate the rate of thermal energy transfer between electrons and acoustic phonons in suspended metallic nanoshells. The electrons are treated as three-dimensional and noninteracting, whereas the vibrational modes are that of an thin cylindrical elastic shell of radius R with a free surface and thickness h. Disorder is neglected. The temperature dependence of the thermal power is obtained analytically for this model, and a crossover from the T3 dependence expected for one-dimensional phonons to a T3/(1 - v2) + 9gammaT4/[T*(1 - v2)(3/2)] dependence is obtained.
- Published
- 2011
16. Surface Enhanced Fluorescence of Physically Polished Nanostructured Metal Surface: The Effect of the Native Oxide Layer
- Author
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Shi-Xian Qu, Hairong Zheng, Hongmin Shao, Gaining Liu, Zhenglong Zhang, and Jun Dong
- Subjects
Materials science ,Quenching (fluorescence) ,Inorganic chemistry ,Biomedical Engineering ,Oxide ,chemistry.chemical_element ,Bioengineering ,General Chemistry ,Condensed Matter Physics ,Fluorescence ,Copper ,Rhodamine 6G ,chemistry.chemical_compound ,Adsorption ,chemistry ,Chemical engineering ,General Materials Science ,Surface plasmon resonance ,Layer (electronics) - Abstract
The fluorescence emission of Rhodamine 6G molecules at the physically polished nanostructured copper surface with varying thickness of the native oxide layer was investigated. The quenching effect was observed when the dye molecule was directly adsorbed onto the substrate surface without the formative oxide layer. However, the fluorescence was enhanced obviously when the native oxide layer was formed at the substrate surface. The experimental observations were discussed by taking into account the formation of the native oxide layer, the non-radiative energy transfer process and the local surface plasmon resonance at rough copper surface. The study highlights the importance of the native oxide layer formed on the metal substrate in surface enhanced fluorescence.
- Published
- 2011
17. Synchronous slowing down in coupled logistic maps via random network topology
- Author
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Shi-Xian Qu, Xing-Sen Wu, Ru-Hai Du, Sheng-Jun Wang, and Tao Jin
- Subjects
Physics ,Multidisciplinary ,Synchronization of chaos ,Chaotic ,Lyapunov exponent ,Topology ,01 natural sciences ,Article ,010305 fluids & plasmas ,symbols.namesake ,Coupling (physics) ,0103 physical sciences ,Synchronization (computer science) ,Attractor ,Orbit (dynamics) ,Dissipative system ,symbols ,010306 general physics - Abstract
The speed and paths of synchronization play a key role in the function of a system, which has not received enough attention up to now. In this work, we study the synchronization process of coupled logistic maps that reveals the common features of low-dimensional dissipative systems. A slowing down of synchronization process is observed, which is a novel phenomenon. The result shows that there are two typical kinds of transient process before the system reaches complete synchronization, which is demonstrated by both the coupled multiple-period maps and the coupled multiple-band chaotic maps. When the coupling is weak, the evolution of the system is governed mainly by the local dynamic, i.e., the node states are attracted by the stable orbits or chaotic attractors of the single map and evolve toward the synchronized orbit in a less coherent way. When the coupling is strong, the node states evolve in a high coherent way toward the stable orbit on the synchronized manifold, where the collective dynamics dominates the evolution. In a mediate coupling strength, the interplay between the two paths is responsible for the slowing down. The existence of different synchronization paths is also proven by the finite-time Lyapunov exponent and its distribution.
- Published
- 2015
18. Cyclic synchronous patterns in coupled discontinuous maps
- Author
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Xingang Wang, Shi-Xian Qu, and Keli Yang
- Subjects
Periodicity ,Discontinuity (linguistics) ,Control theory ,Linear Models ,Cluster (physics) ,Feature (machine learning) ,Linear model ,Computer Simulation ,Models, Theoretical ,Biological system ,Synchronization ,Mathematics - Abstract
Cyclic collective behaviors are commonly observed in biological and neuronal systems, yet the dynamical origins remain unclear. Here, by models of coupled discontinuous map lattices, we investigate the cyclic collective behaviors by means of cluster synchronization. Specifically, we study the synchronization behaviors in lattices of coupled periodic piecewise-linear maps and find that in the nonsynchronous regime the maps can be synchronized into different clusters and, as the system evolves, the synchronous clusters compete with each other and present the recurring process of cluster expanding, shrinking, and switching, i.e., showing the cyclic synchronous patterns. The dynamical mechanisms of cyclic synchronous patterns are explored, and the crucial roles of basin distribution are revealed. Moreover, due to the discontinuity feature of the map, the cyclic patterns are found to be very sensitive to the system initial conditions and parameters, based on which we further propose an efficient method for controlling the cyclic synchronous patterns.
- Published
- 2015
19. Majorization relation in quantum critical systems
- Author
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Wen-Li Yang, Heng Fan, Shi-Xian Qu, Yu-Ran Zhang, Si-Yuan Liu, and Lin-Ping Huai
- Subjects
Quantum phase transition ,Physics ,LOCC ,Phase transition ,Quantum Physics ,Convertibility ,General Physics and Astronomy ,FOS: Physical sciences ,Quantum entanglement ,Rényi entropy ,Ising model ,Statistical physics ,Quantum Physics (quant-ph) ,Quantum - Abstract
The most basic local conversion is local operations and classical communications (LOCC), which is also the most natural restriction in quantum information processing. We investigate the conversions between the ground states in quantum critical systems via LOCC and propose an novel method to reveal the different convertibility via majorization relation when a quantum phase transition occurs. The ground-state local convertibility in the one-dimensional transverse field Ising model is studied. It is shown that the LOCC convertibility changes nearly at the phase transition point. The relation between the order of quantum phase transitions and the LOCC convertibility is discussed. Our results are compared with the corresponding results using the Renyi entropy and the LOCC convertibility with assisted entanglement., Comment: 4 pages, 4 figures
- Published
- 2015
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20. Dynamical processes of Ln3+ ions doped in LaF3 nanocrystals embedded in transparent oxyfluoride glass
- Author
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Richard S. Meltzer, Shi-Xian Qu, Matthew John Dejneka, Xiaojun Wang, and Hairong Zheng
- Subjects
Materials science ,Photoluminescence ,Energy transfer ,Doping ,Biophysics ,Mineralogy ,General Chemistry ,Condensed Matter Physics ,Biochemistry ,Atomic and Molecular Physics, and Optics ,Ion ,Nanocrystal ,Chemical physics ,Excited state ,Rare earth ions ,Energy transfer rate - Abstract
The transverse and longitudinal relaxations from the excited electronic levels of rare earth ions (Ln 3+ ) in nanocrystals are reviewed. Employing the frequency up-converted emission, we have studied the ion–ion interactions and the distribution of the ions within Pr 3+ :LaF 3 nanocrystals embedded in oxyfluoride glass. The phonon-assisted energy transfer between Pr 3+ ions is discussed and the relation between the energy transfer rate and the buildup of the up-converted emission is established. The results suggest that the Pr 3+ concentration inside the nanocrystals is 5–10 times that of the average concentration. A jump in the energy transfer rate is observed as the concentration increases, and the possible processes behind it are discussed.
- Published
- 2006
21. DISSONANCE OF MULTIPLE DEVIL'S STAIRCASES
- Author
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Da-Ren He, Xu-Ming Wang, and Shi-Xian Qu
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Pure mathematics ,Property (philosophy) ,Applied Mathematics ,Consonance and dissonance ,Function (mathematics) ,Parameter space ,Tower (mathematics) ,Phase locking ,Smooth curves ,Modeling and Simulation ,Cognitive dissonance ,Engineering (miscellaneous) ,Algorithm ,Mathematics - Abstract
The multiple Devil's staircase reported by Qu, Wu and He in 1997 was composed of many tower-like structures. Each of which include two branches of the conventional complete Devil's staircases that connect the "single-exit" top and bottom steps. Their analytic conclusion show that all the conventional Devil's staircases are confined by two smooth curves with similar function forms W ∝ 1/ln ∊. These may be addressed as a kind of consonance. Our recent study found that it happens only in a few cases. Actually, in their system, 16 different kinds of tower branches exist in most parts of the parameter space. A lot of the steps lose the consonant property which are the so-called dissonant structures. The number of types of the corresponding dissonant branches is employed to describe the dissonance of the staircase. When the number of the discontinuous regions n, in the system develops, the dissonance of the staircase increases with 2n3- n rule. The numerical result shows that the conclusion is valid for a general discontinuous circle map.
- Published
- 2005
22. Dissonant structures of multiple devil's staircases in one-dimensional discontinuous maps
- Author
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Xu-Ming Wang, Shi-Xian Qu, Zheng-Xin Zhou, Jian-Shan Mao, and Da-Ren He
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Consonant ,Physics ,General Physics and Astronomy ,Geometry ,Consonance and dissonance ,Function (mathematics) ,Parameter space ,Tower - Abstract
The multiple devil's staircase, that was observed in 1997 in a one-dimensional map with two discontinuous regions, showed a kind of consonant tower-like structures. All the branches that connected top and bottom phase-locked steps of the towers could be divided into two kinds. Our recent study found that actually 16 different kinds of tower branches existed in most parts of parameter space. 14 of them belong to the so-called dissonant structures. The number of types of corresponding dissonant branches is employed to describe the dissonance of the staircase. When the number of discontinuous regions, n, in the system function develops, the dissonance of the staircase increases with 2n3−n rule.
- Published
- 2002
23. Multifractal phase transition in the Davidson–Cole relaxation process
- Author
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Alexander Leyderman, Hairong Zheng, Alfonso Barrientos, and Shi-Xian Qu
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Physics ,Phase transition ,Fractal ,Condensed matter physics ,Triple point ,Relaxation (NMR) ,General Physics and Astronomy ,Multifractal system ,Dielectric ,Measure (mathematics) ,Cole–Cole equation - Abstract
A multifractal measure for the relaxation time distribution in Davidson–Cole dielectric relaxation is analytically obtained. A general first-order multifractal phase transition is reported. It is characterized by the existence of three different phases and the corresponding triple point.
- Published
- 2000
24. Multiple devil’s staircase and type-V intermittency
- Author
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Shunguang Wu, Shi-Xian Qu, and Da-Ren He
- Subjects
Nonlinear Sciences::Chaotic Dynamics ,law ,Intermittency ,Attractor ,Chaotic ,Monotonic function ,Geometry ,Tree (set theory) ,Parameter space ,Type (model theory) ,Plateau (mathematics) ,law.invention ,Mathematics - Abstract
We have observed a ``multiple devil's staircase'' in a one-dimensional (1D) map including two discontinuous regions. Both end points of each phase-locked plateau in the staircase are confined by the conditions of collision between the periodic orbit and one of the discontinuous region edges. There are more modes of the collision than in a 1D map including only one discontinuous region. This complexity makes the whole staircase lose monotonicity, self-similarity, and the ``Farey tree rule'' for a description of the plateau length distribution. However, the staircase consists of many conventional complete devil's staircases, many of them having their own threshold of transfer to chaos via a type-V intermittency. Therefore the parameter space can be divided into three parts. In the first part only periodic attractors appear. In the second part periodic and chaotic attractors appear alternatively, and the system displays type-V intermittency frequently. In the last part only chaotic attractors exist.
- Published
- 1998
25. A multiple devil's staircase in a discontinuous map
- Author
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Da-Ren He, Shi-Xian Qu, and Shunguang Wu
- Subjects
Physics ,Property (philosophy) ,Farey tree ,Mathematical analysis ,Relaxation oscillator ,General Physics and Astronomy ,Ising model ,Monotonic function ,Length distribution ,Plateau (mathematics) - Abstract
This letter reports the specific phase-locking property of a 1-d map that includes two discontinuous regions. The devil's staircase observed in the system loses monotonicity, self-similarity, and the “Farey tree rule” for description of the plateau length distribution. However this staircase is composed of many conventional devil's staircases that have all three characteristics.
- Published
- 1997
26. Escaping from Strange Sets in Discontinuous Circle Map
- Author
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Da-Ren He, Jian-gang Sun, Shi-xian Qu, Shan Guan, Xi-ping Ji, and Bing-Hong Wang
- Subjects
Nonlinear Sciences::Chaotic Dynamics ,Physics ,Discontinuity (linguistics) ,Scaling law ,Mathematics::Dynamical Systems ,Classical mechanics ,Mathematical analysis ,Attractor ,Life time ,General Physics and Astronomy ,Leakage (electronics) - Abstract
The leakage of iterations from chaotic attractor near crisis due to dynamical interaction between discontinuity and noninvertibility has been studied. The scaling law of the mean life time is derived analytically. The numerical result shows very good agreement.
- Published
- 1996
27. Hole-induced crisis in a piece-wise linear map
- Author
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B. Christiansen, Shi-Xian Qu, and Da-Ren He
- Subjects
Physics ,Piece wise linear ,Linear map ,Josephson effect ,Classical mechanics ,Attractor ,General Physics and Astronomy ,Function (mathematics) ,Diffusion (business) ,Collision ,Scaling - Abstract
An interior crisis with striking new characteristics has been observed in a one-dimensional piece-wise linear map. Induced by the collision between a chaotic attractor and a “hole”, the crisis exhibits a scaling law of the characteristic time as 〈 τ 〉 ∼ ϵ −1 . The analytical calculation shows that this scaling behavior sensitively depends on the function form of the map and suggests that a different and more complicated scaling behavior may be observed in some non-linear maps.
- Published
- 1995
28. Influence of the Surface Structure and Vibration Mode on the Resistivity of Cu Films
- Author
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Ke Xia, Shi-Xian Qu, and Ya-Ni Zhao
- Subjects
Surface (mathematics) ,Physics ,Condensed matter physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Scattering ,FOS: Physical sciences ,General Physics and Astronomy ,Atom vibrations ,Vibration ,symbols.namesake ,Amplitude ,Electrical resistivity and conductivity ,Normal mode ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,symbols ,Debye model - Abstract
The influence of the surface structure and vibration mode on the resistivity of Cu films and the corresponding size effect are investigated. The temperature dependent conductivities of the films with different surface morphologies are calculated by the algorithm based upon the tight-binding linear muffin-tin orbital method and the Green's function technique. The thermal effect is introduced by setting the atomic displacements according to the Gaussian distribution with the mean-square amplitude estimated by the Debye model. The result shows that the surface atomic vibration contributes significantly to the resistivity of the systems. Comparing the conductivities for three different vibration modes, it is suggested that freezing the surface vibration is necessary for practical applications to reduce the resistivity induced by the surface electron-phonon scattering.
- Published
- 2011
29. Local-field effect on the fluorescence relaxation of Tm3+:LaF3 nanocrystals immersed in liquid medium
- Author
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Enjie He, Hairong Zheng, Shi-Xian Qu, and Xisheng Zhang
- Subjects
Glycerol ,Materials science ,Ethanol ,Surface Properties ,Doping ,Relaxation (NMR) ,Biophysics ,Analytical chemistry ,Water ,Benzene ,Fluorescence ,Hydrothermal circulation ,Ion ,Nanostructures ,Fluorides ,Nanocrystal ,Chemistry (miscellaneous) ,Lanthanum ,Carbon Disulfide ,Thulium ,Luminescent Measurements ,Exponential decay ,Particle Size ,Local field - Abstract
Tm(3+):LaF(3) nanocrystals were synthesized with hydrothermal technique. Local-field effect on the radiative relaxation rate was studied in the system of Tm(3+):LaF(3) nanocrystals immersed in several liquid media. The fluorescence lifetime was measured. It was found that the fluorescence decay presented the characteristics of second-order exponential decay, for which the contribution from the ions inside the nanocrystal and ions at the interface of the nanocrystal were distinguished. Investigating the experimental results with proposed models, we found that the surface effect had to be eliminated. For rare earth doped LaF(3) nanocrystals, real-cavity model well explains the influence of surrounding medium on the fluorescence relaxation rate.
- Published
- 2009
30. Scaling Properties of the Period-Adding Sequences in a Multiple Devil's Staircase
- Author
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Shunguang Wu, Cai-yun Wu, Da-Ren He, and Shi-Xian Qu
- Subjects
Physics ,Sequence ,Period (periodic table) ,Position (vector) ,General Physics and Astronomy ,Statistical physics ,Plateau (mathematics) ,Scaling - Abstract
In this letter the scaling properties of the period-adding sequences in a so-called "multiple Devil's staircase" are reported. It is certified both analytically and numerically that the width of the i-th phase-locked plateau in a sequence scales as ln|Δe(i)| ∝ i, and the position of the plateau scales as ln|e∞ - ei| ∝ i. These properties are qualitatively different from those of the period-adding sequences in conventional Devil's staircases.
- Published
- 1998
31. Hot electrons in low-dimensional phonon systems
- Author
-
Andrew Cleland, Michael R. Geller, and Shi-Xian Qu
- Subjects
Elastic scattering ,Physics ,Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Mean free path ,Phonon ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Coupling (probability) ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Standard Model ,Free surface ,Molecular vibration ,0103 physical sciences ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Condensed Matter::Strongly Correlated Electrons ,Atomic physics ,010306 general physics ,0210 nano-technology ,Scaling - Abstract
A simple bulk model of electron-phonon coupling in metals has been partially successful in explaining experiments on metal films that actually involve surface- or other low-dimensional phonons. However, by an exact application of this standard model to a semi-infinite substrate with a free surface, making use of the actual vibrational modes of the substrate, we show that such agreement is fortuitous, and that the model actually predicts a low-temperature crossover from the familiar ${T}^{5}$ temperature dependence to a stronger ${T}^{6}\phantom{\rule{0.2em}{0ex}}\mathrm{log}\phantom{\rule{0.2em}{0ex}}T$ scaling. Comparison with existing experiments suggests a widespread breakdown of the standard model of electron-phonon coupling in metals.
- Published
- 2005
- Full Text
- View/download PDF
32. Mesoscopic electron and phonon transport through a curved wire
- Author
-
Michael R. Geller and Shi-Xian Qu
- Subjects
Physics ,Condensed Matter - Materials Science ,Mesoscopic physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Helmholtz equation ,Condensed matter physics ,Quantum wire ,Scalar (physics) ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Wave equation ,Curvature ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Classical mechanics ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Scattering theory ,Boundary value problem ,010306 general physics ,0210 nano-technology - Abstract
There is great interest in the development of novel nanomachines that use charge, spin, or energy transport, to enable new sensors with unprecedented measurement capabilities. Electrical and thermal transport in these mesoscopic systems typically involves wave propagation through a nanoscale geometry such as a quantum wire. In this paper we present a general theoretical technique to describe wave propagation through a curved wire of uniform cross-section and lying in a plane, but of otherwise arbitrary shape. The method consists of (i) introducing a local orthogonal coordinate system, the arclength and two locally perpendicular coordinate axes, dictated by the shape of the wire; (ii) rewriting the wave equation of interest in this system; (iii) identifying an effective scattering potential caused by the local curvature; and (iv), solving the associated Lippmann-Schwinger equation for the scattering matrix. We carry out this procedure in detail for the scalar Helmholtz equation with both hard-wall and stress-free boundary conditions, appropriate for the mesoscopic transport of electrons and (scalar) phonons. A novel aspect of the phonon case is that the reflection probability always vanishes in the long-wavelength limit, allowing a simple perturbative (Born approximation) treatment at low energies. Our results show that, in contrast to charge transport, curvature only barely suppresses thermal transport, even for sharply bent wires, at least within the two-dimensional scalar phonon model considered. Applications to experiments are also discussed., 9 pages, 11 figures, RevTex
- Published
- 2004
33. Calorimetric studies of the crystallization process of N-nitrophenyl-L-prolinol
- Author
-
C. A. Condat, Shi-Xian Qu, Nora Ortega, and Alexander Leyderman
- Subjects
Materials science ,Isothermal crystallization ,Thermodynamics ,Calorimetry ,Isothermal process ,law.invention ,Prolinol ,chemistry.chemical_compound ,Differential scanning calorimetry ,chemistry ,law ,Organic glass ,Crystallization ,Glass transition - Abstract
The crystallization of the N-4-nitrophenyl-L-prolinol (NPP) organic glass was investigated by differential scanning calorimetry (DSC). The results showed the influence of temperature and temporal treatment of the melt on the crystallization processes obtained while cooling from the liquid or d uring heating from the glass state. The behavior of the crystallization kinetics from the glass state was studied under both nonisothermal and isothermal conditions. On the first case, DSC thermograms were recorded at heating rates from 2 to 40oC/min. The crystallization temperature was found to depend on heating rates. Two crystallization phases have been found during the heating of the sample from the glass-like disordered states in the continuing cycling of DSC. In the second case, isothermal crystallization was observed at temperatures ranging between the glass transition and crystallization points.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
- Published
- 2002
34. Stochastic resonance in a discrete neuron with time delay and two different modulation signals
- Author
-
Ke Li Yang, Can Jun Wang, and Shi Xian Qu
- Subjects
Physics ,Amplitude ,Stochastic resonance ,Modulation ,Noise (signal processing) ,Rulkov map ,Condensed Matter Physics ,Topology ,Signal ,Fourier series ,Mathematical Physics ,Atomic and Molecular Physics, and Optics ,Group delay and phase delay - Abstract
Stochastic resonance in an excitable neuron based on the Rulkov map with noise, delay feedback, low-frequency signal and high-frequency signal is investigated numerically. The results show that there exist an optimal noise intensity, optimal time delay and optimal amplitude of the high-frequency signal at which the phase synchronisation between the low-frequency input signal and the output signal is the best. The Fourier coefficient is calculated to measure the stochastic resonance. It is found that the existence of a maximum in the , and plots is the identifying characteristic of the stochastic resonance phenomenon.
- Published
- 2014
35. Time-Delay Enhanced Coherence Resonance in a Discrete Neuron with Noises
- Author
-
Ke-Li Yang, Can-Jun Wang, and Shi-Xian Qu
- Subjects
Physics ,Time delays ,Computer simulation ,business.industry ,Gaussian ,General Physics and Astronomy ,Noise intensity ,Intensity (physics) ,symbols.namesake ,Optics ,Colors of noise ,Coherence resonance ,symbols ,business - Abstract
Coherence resonance in a discrete excitable neuronal model with noises and time delays is investigated. The effects of the time delays on coherence resonance are revealed in two cases: Gaussian white and Gaussian color noises, respectively. The coefficient of variation of interspike intervals is calculated by numerical simulation. The results show that the coherence resonance is enhanced with the time delay increasing in the weak noises intensity cases, while there is no effect in the large noise intensity. Moreover, the coherence resonance can be held back by the self-correlation time, when the system is driven by a color noise.
- Published
- 2014
36. Partial and complete periodic synchronization in coupled discontinuous map lattices
- Author
-
Shi-Xian Qu, Ke-Li Yang, Tao Jin, Hui-Yun Chen, and Wei-Wei Du
- Subjects
Physics ,Series (mathematics) ,Mathematical analysis ,Synchronization (computer science) ,General Physics and Astronomy ,Order (ring theory) ,Motion (geometry) ,Expression (mathematics) - Abstract
The partial and complete periodic synchronization in coupled discontinuous map lattices consisting of both discontinuous and non-invertible maps are discussed. We classify three typical types of periodic synchronization states, which give rise to different spatiotemporal patterns including static partial periodic synchronization, dynamically periodic synchronization, and complete periodic synchronization patterns. A special prelude dynamics of partial and complete periodic synchronization motion, which is shown by five separated concave curves in the time series plots of the order parameters, is observed. The detailed analysis shows that the special prelude dynamics is induced by the competition between two synchronized clusters, and the analytical expression for the corresponding order parameter is obtained.
- Published
- 2014
37. Bifurcation diagram globally underpinning neuronal firing behaviors modified by SK conductance
- Author
-
Shi-Xian Qu, Wei Ren, Meng-Jiao Chen, Heng-Li Ling, and Yihui Liu
- Subjects
Physics ,Quantitative Biology::Neurons and Cognition ,General Physics and Astronomy ,Conductance ,Depolarization ,Bifurcation diagram ,Apamin ,SK channel ,chemistry.chemical_compound ,medicine.anatomical_structure ,nervous system ,chemistry ,Modulation ,medicine ,Biophysics ,Neuron ,Bifurcation - Abstract
Neurons in the brain utilize various firing trains to encode the input signals they have received. Firing behavior of one single neuron is thoroughly explained by using a bifurcation diagram from polarized resting to firing, and then to depolarized resting. This explanation provides an important theoretical principle for understanding neuronal biophysical behaviors. This paper reports the novel experimental and modeling results of the modification of such a bifurcation diagram by adjusting small conductance potassium (SK) channel. In experiments, changes in excitability and depolarization block in nucleus accumbens shell and medium-spiny projection neurons are explored by increasing the intensity of injected current and blocking the SK channels by apamin. A shift of bifurcation points is observed. Then, a Hodgkin—Huxley type model including the main electrophysiological processes of such neurons is developed to reproduce the experimental results. The reduction of SK channel conductance also shifts the bifurcations, which is in consistence with experiment. A global bifurcation paradigm of this shift is obtained by adjusting two parameters, intensity of injected current and SK channel conductance. This work reveals the dynamics underpinning modulation of neuronal firing behaviors by biologically important ionic conductance. The results indicate that small ionic conductance other than that responsible for spike generation can modify bifurcation points and shift the bifurcation diagram and, thus, change neuronal excitability and adaptation.
- Published
- 2014
38. Multifractal phase transitions in the non-debye relaxation processes
- Author
-
Shi-Xian Qu and Alexander Leyderman
- Subjects
Physics ,Phase transition ,Fractal ,Distribution function ,Exponent ,Relaxation (physics) ,Multifractal system ,Dielectric ,Statistical physics ,Cole–Cole equation - Abstract
The multifractal measures of the relaxation-time distributions are analytically obtained for some typical non-Debye dielectric relaxation processes. The characteristics of the corresponding multifractal thermodynamics are discussed. It is shown that the probability of the relaxation times near the poles of their distribution function is fractal scaling. The corresponding Lipschitz-H\"old singular exponent is, or can be, determined by the so-called shape parameters in the empirical dielectric relaxation formulas. The relationship to some analytical proofs of the empirical dielectric formulas based upon the fractal models is also analyzed. Some generalized multifractal phase transitions with interesting features are reported in this paper. The recent experiment results on the molten-crystal transition in organic glass systems are also discussed to support our conclusions.
- Published
- 2000
39. Surface enhanced fluorescence on three dimensional silver nanostructure substrate
- Author
-
Gaining Liu, Zhenglong Zhang, Shi-Xian Qu, Jun Dong, Hairong Zheng, Meicen Liu, and Xiaoqing Yan
- Subjects
Fluorophore ,Nanostructure ,Materials science ,General Physics and Astronomy ,Substrate (chemistry) ,Nanoparticle ,Nanotechnology ,Photochemistry ,Fluorescence ,Silver nanoparticle ,Rhodamine 6G ,chemistry.chemical_compound ,chemistry ,Surface plasmon resonance - Abstract
Multi-dimensional metallic nanostructures were fabricated by self-assembling silver nanoparticles on 3-aminopropyltrimethoxysilane-modified glass substrate and using p-aminothiophenol molecule as a linker. Surface enhanced fluorescence was investigated for Rhodamine 6G fluorophore molecules on the prepared 2D and 3D substrates. The experimental observation showed that the 3D nanostructured substrate presented stronger fluorescence enhancement, comparing with what was observed on the 2D nanoparticle arrays. Higher intensity of local electric field and stronger coupling of surface plasmon resonance in 3D silver nanostructure enhanced the excitation and emission of fluorophore molecules more effectively, leading to a stronger fluorescence enhancement on 3D nanostructured substrate. The result suggests that a metallic substrate with 3D nanostructures can produce better fluorescence enhancement, which is important for studying the mechanism and expanding the potential applications of enhanced fluorescence effect.
- Published
- 2012
40. Erratum to: 'Multifractal phase transition in the Davidson–Cole relaxation process'
- Author
-
Hairong Zheng, Shi-Xian Qu, Alexander Leyderman, and Alfonso Barrientos
- Subjects
Physics ,Phase transition ,Condensed matter physics ,Relaxation process ,General Physics and Astronomy ,Multifractal system - Published
- 2000
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